// model User class
Ext.define("User", {
	extend: "Ext.data.Model",
	fields: [
		{name: 'name', type:'string', sortable:true},
		{name: 'age', type:'int', sortable:true},
		{name: 'email', type:'string', sortable:true},
		]
});

Ext.create("Ext.data.Store", {
	model: 'User',
	storeId: 'user_id',
	proxy: {
		type: 'ajax',  //代理模式ajax and json
		url: '',
		reader: {
			type: 'json',
			root: 'topics'
		},
		writer: {
			type: 'json'
		}
	},
	auto: true
});